This used to happen with my knees when I was doing squats but that seems to have cleared up somehow (?) but now when Im doing such exercises as dumbbell front raises the left and only the left arm will click pretty noisily on each rep and feels uncomfy in the process. I have tried different variations in position, but cant find one where I can consistently do the exercise without the click. What is it and why is it doing it and should I be worried (perhaps of arthritis if it does this for years)? Also why did I have it in my knees on squats and now it stopped, not that I'm complaining :)?